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TT: Fachverband Tiefe Temperaturen
TT 14: Superconductivity: Properties and Electronic Structure
TT 14.1: Vortrag
Montag, 9. März 2026, 15:00–15:15, HSZ/0103
Tuning the superconducting dome in granular aluminum thin films — Aniruddha Deshpande, Jan Pusskeiler, Christian Prange, Uwe Rogge, Martin Dressel, and •Marc Scheffler — 1. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
The peculiar superconducting properties of granular aluminum, which consists of nanometer-sized aluminum grains separated by aluminum oxide, are attractive for applications in quantum circuitry, and they are interesting from a fundamental materials physics view. The phase diagram of granular aluminum as a function of normal-state resistivity features a superconducting dome with a maximum critical temperature Tc well above the Tc = 1.2 K of pure aluminum. We show how the maximum of this superconducting dome grows if the substrate temperature during deposition is lowered from 300 K to cooling with liquid nitrogen (150 and 100 K) and liquid helium (25 K). The highest Tc that we observe is 3.27 K [1]. These results highlight that granular aluminum is a model system for complex phase diagrams of superconductors and demonstrate its potential in the context of high kinetic inductance applications, where materials properties can be carefully tuned by optimized thin-film growth [2]. This is augmented by our observation of comparably sharp superconducting transitions of high-resistivity samples grown at cryogenic temperatures and by a thickness dependence even for films substantially thicker than the grain size [1].
[1] A. Deshpande et al., J. Appl. Phys. 137 (2025) 013902
[2] A. Deshpande et al., Physica C 634 (2025) 1354709
Keywords: granular aluminum; granular superconductors; disordered superconductors; superconducting thin films; high kinetic inductance